Cardiovascular death and morbidity continue to be major longterm complications in renal transplant recipients. The importance of lipid and lipoprotein abnormalities as risk factors for the development of cardiovascular disease will be assessed. In addition to total, LDL and HDL-cholesterol and triglycerides, the role of apoproteins A1 and B, Lp(a) and lipoprotein composition (in a subset of patients) will be determined. Other risk factors will also be measured and, thus, the independent effect of lipid and lipoprotein abnormalities on long term outcomes can be assessed in these studies. Three interdependent studies will be performed. 1) All pediatric ( < 18 years of age) recipients of renal transplants will be studied before and with sequential observations posttransplantation. It is postulated that lipid abnormalities occur frequently and persist despite good allograft function. 2) A crosssectional study of 200 randomly selected adults with a functioning graft 1 year will be done in years 1 and 2. The frequency and type of lipid abnormalities plus other risk factors will be determined. This data will also be used to develop the final design of the lipid interventional trial. 3) A lipid interventional trial will be initiated in year 3 in adults age 30-59 years with elevated LDL-cholesterol levels. The effect of lipid intervention on cardiovascular mortality and morbidity, and longterm rejection will be studied. Additionally the safety of lipid-lowering drugs, frequency of side effects and interaction with other drugs will be assessed.